Does 2.3 beneift from Hyperthreading Enabled?

Any issues, problems or troubleshooting topics related to the Prepar3D client application.
gjharrall
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Postby gjharrall » Tue Aug 12, 2014 2:16 pm

I know the affinity mask tweak is no longer required in 2.3 but does enabling hyper-threading have any benefits?



Thanks,



Glenn

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Beau Hollis
Lockheed Martin
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Postby Beau Hollis » Tue Aug 12, 2014 3:20 pm

Yes. There are varied opinions out there of course depending on what kind of tests are being run, but you should see better paging performance using all cores. Our default affinity mask now uses all cores including HT cores. There may be some benefit to masking off the first HT core to give the primary thread more breathing room and/or masking off one core completely to trick the OS into not schedule tasks on the Prepar3D cores. All that said, the best one-size-fits-all setting we found given the current job scheduling technique is to let all cores work.
Beau Hollis
Prepar3D Software Architect

DylanM
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Postby DylanM » Tue Aug 12, 2014 3:42 pm

Really informative Beau, and thanks to you (and team) for the excellent work on 2.3. She's a beaut...

hermes82
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Postby hermes82 » Tue Aug 12, 2014 5:37 pm

I just gave hyperthreading a try and it seems to be of no benefit, i'm running an i7 2700k and went from 40 fps down to a max of 27, disabled hyperthreading in the boot menu and frame rates came back up again, tried with and without core 0 but no change, guess i'll leave it off for now

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BG2518
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Postby BG2518 » Wed Aug 13, 2014 2:04 am

Beau,



Lots of folk were using various ways to switch on all cores prior to v2.3 and now we see you've finally allowed the app to use all cores (great) and I'm sure this has made the sim more fluid.



What I think you did say a while back was that you didn't really want to do this (esp. on the first core) as other apps may suffer and/or have problems.



Well, I can say that another app "may" be experiencing a problem now, namely PLAN G.



I've only run v2.3 half a dozen times so far and have had 2 instances of PLAN G not responding and had to shut it down.



I'm not too concerned - it just may be coinsidence.



I just thought I'd throw that out there to remind folk so they keep an eye out for such things ??



It may not apply, do tell.



Great work, many thanks.



BG2518 - Bob.

Kosta
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Postby Kosta » Wed Aug 13, 2014 4:35 am

Bob, and easy way to test this is to turn off the Core0 by AM and see if PlanG is working normally. Would be interesting.

Japo32
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Postby Japo32 » Wed Aug 13, 2014 5:06 am

I always don't know what number to put.. I have HT enabled with 8 virtual procesors, beeing 4 physical ones. What is the number I have to put to not use core0?



Thanks!


Kosta
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Postby Kosta » Wed Aug 13, 2014 5:53 am

LOL, I don't get it why it's so hard to set the AM. I guess you don't know is because you never wanted to know. I even have an extensive explanation on my blog (and it's really easy using the windows calc). All the same:

84 or 252 (latter is using HT cores).

overload
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Postby overload » Wed Aug 13, 2014 6:52 am

For a one off test - wouldn't it be easier to select P3D from the processes list in task manager - then right click - select "set affinty" from the drop down list - and tick/un-tick whichever cores you want?

Eugene

Zach Heylmun
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Postby Zach Heylmun » Wed Aug 13, 2014 8:15 am

We don't elevate our process priority, so Prepar3D won't choke other applications for processing resources. I would be very surprised if our changes to the default affinity mask caused any trouble in that respect Mr. Bob. Honestly, I would recommend giving the default configuration a good thorough chance, because we changed more than just the affinity mask to improve processor utilization. Our internal work scheduling should allow hyper threaded processors to realize improved paging performance without overloading the first physical core and lowering the frame-rate.

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BG2518
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Postby BG2518 » Wed Aug 13, 2014 8:35 am

It's great that you fully explain your answer as I'm sure the whole P3D community will appreciate that !!!



I have had no further issues so it is likely just teething trouble.



Many thanks for a sim that lets me FLY !!!!!



BG2518 - Bob.

Kosta
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Postby Kosta » Wed Aug 13, 2014 9:30 am

I can also see that running all cores has now been improved. I have been using AM=15 on my v2.2 and 4-core CPU/no HT, however in v2.3, I see things are better. Also (and this is really just a preliminary test), I see higher framerates across sceneries in P3D. I am making progress on my platforms.

thejoe
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Postby thejoe » Wed Aug 13, 2014 12:04 pm

Has anyone tried this on a dual Xeon system? With HT enabled, I can get 16 cores. What about giving P3D its own processor, the last 8 cores for example? I would be interested if anyone has a clue. Kosta, any experience with this?

Kosta
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Postby Kosta » Wed Aug 13, 2014 12:48 pm

No experience with such setups, however I don't see it working faster than it does now. If you would expect faster framerates, then it would all be the same. The only relevant core that "does" the FPS, is the Core0 or Core1, depending on which you place it. The further you "move" that first core, the less texture threads you have.

As I test around, I noticed that only core running at 100% is currently the Core0, and from that, I must conclude that FPS come from it, or better said, depend on it. However, it probably ain't as simple as I'm putting it down here.



This system is the system how it has been working until now. Maybe something changed in the v2.3, and this is something only LM can answer.



IMO, the best solution for the P3D is a hexa-core with the highest frequency possible and a monster GPU beside it. I will probably go for 4790K @ 4.6 and GTX780TI if I manage the funds.

Saul
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Postby Saul » Wed Aug 13, 2014 3:43 pm



Quote:

Quote from thejoe on August 13, 2014, 12:04

Has anyone tried this on a dual Xeon system? With HT enabled, I can get 16 cores. What about giving P3D its own processor, the last 8 cores for example? I would be interested if anyone has a clue. Kosta, any experience with this?




I have P3D on a Dual Xeon E5-2690 V2, currently with v2.3 P3D is using 32 cores of my systems 40 cores.

32 core is the maximum that any 32Bit application can use.



As for performance vs my other system with is a 12 core i7 690x OC to 4.2GHz is very similar FPS with 1 distinction.

That the smoothness on the Xeon system is much better.


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